Stephen Gaghan struck gold five years ago when he penned the screenplay for Traffic, one of the most important films of the new millennium. Now he repeats the trick, this time as writer and director of Syriana, an equally ambitious and no less successful examination of the oil industry. With deft strokes, he paints a huge canvas populated by spies, executives, sheiks, and day laborers, all of them chasing after the power and influence that stems from controlling the world's precious supply of energy. It's overwhelming in its scope, tying together countless threads and hidden corners into a single all-encompassing vision. The results demand much from the audience: attention, thoughtfulness, and the ability to think critically and question what lies beneath the surface of the action. But for those willing to devote themselves to the effort, the film returns the investment tenfold.

The thesis is simple. We're addicted to oil and there's not enough to go around. The largest reserves lie in the most unstable region of the globe: beset by poverty, ruled by thugs and fanatics, and subject to the ruthless intrusions of world powers who need the local resources to function. From that basic truth spins a breathtakingly complex reality, devoid of nobility and ruled solely by the laws of the jungle. We see it from several key perspectives. Bob Barnes (George Clooney) is a devoted CIA agent, with extensive knowledge of the Middle East and a willingness to get his hands dirty for king and country. Prince Nasir (Alexander Siddig) is the heir to an unnamed Arabian kingdom who sells his nation's oil rights to the Chinese when they outbid a giant U.S. company called Connex. Jimmy Pope (Chris Cooper) owns a smaller oil company that signs a shifty deal for rights in Kazakhstan, and is immediately targeted by Connex for a merger. Bennett Holiday (Jeffrey Wright) is a lawyer charged with investigating said merger to see if it passes U.S. laws. Byran Woodman (Matt Damon) is a reform-minded energy executive who becomes allies with Nasir after a tragic accident on the prince's estate. And seemingly unnoticed beneath them all is Wasim (Mazhar Munir), a Pakistani oil worker who loses his job and falls under the influence of a charismatic recruiter with big plans and a need for martyrs.

Gaghan gives all of these figures reasonable motivations, driven by personal ideology yet impacted by the practical needs of reality. Each has their own agenda -- selfish in many cases, but also embracing their own particular morality -- that slowly but surely entangles them in increasingly compromised positions. At times, the big picture is submerged beneath their personal perceptions, and though we never lose track of why they're behaving the way they do, their part in the larger puzzle can be difficult to spot. Yet Syriana is always internally consistent and its inner workings, though enigmatic at times, never violate the tenets of logic. Gaghan's direction lacks the formalistic tics of Steve Soderbergh's in Traffic, utilizing straightforward blocking and the expected fly-on-the-wall vérité typical of movies like this. But it works because it doesn't add any undue complexity to a drama already challenged by multiple plot threads and constant crosscutting. The nuts-and-bolts action stays clear and illuminates -- with careful, methodical precision -- the grander vision that Gaghan is trying to express.

And it's a pretty grim vision. Darwinism runs rampant, fueled by staggering amounts of money and an unspoken need to grab what you can before the pumps run dry. America engages in nation building without the slightest sense of how to go about it, driven only by the need to keep gas prices low. Middle Eastern rulers pocket the cash and live lives of grotesque luxury while their citizens are starving beneath them. Even reformers feel the pull of forces beyond their control, and their efforts to make things better come at a disastrous price. Everyone is accountable for the problem in some way or another. Certainly, the West takes its share of lumps -- and we, the consumers who fill up at the pump every day, are the film's unindicted co-conspirators -- but the mess goes beyond a single culture or administration. It's built into the very fabric of modern civilization, a piece of darkness engendered by an imperfect world. The system is dysfunctional because so much is at stake, and ethics become a luxury that no one can afford. "Corruption," as one character puts it, "is why you and I are prancing around in here instead of fighting over scraps of meat out in the street." As long as we need gas to run our cars or power our generators, it will not change. And as supplies slowly dwindle, the film assures us, it will only get worse.

The cast is first-rate, but I want to draw special attention to Siddig, little known outside the ranks of Star Trek fans. Since leaving that franchise, he has charted a brave and very admirable course for himself, consistently choosing roles that illuminate Middle Eastern characters in complex and interesting ways. It couldn't have been easy to ferret them out amid the one-note cabbies and evil terrorists, but his perseverance pays off in this, his most thoughtful and detailed performance to date. Nasir is a benevolent man with grand plans for his emirate, but his position -- like all the others in the film -- holds dark undercurrents; Siddig develops them alongside his character's brighter aspects without diminishing either side, giving the film a strangely appropriate moral compass.

The bulk of the credit, however, goes to Gaghan, who knows this subject inside and out, and who brings remarkable expertise to its depiction on-screen. Like Traffic, Syriana is a vital roadmap to a very important issue, using the power of cinema to convey it in a visceral (though often challenging) way. This is how agenda filmmaking is supposed to work: respecting its audience enough to stimulate their minds, rather than telling them what to think. Syriana never presumes to solve the problem, nor does it provide comforting answers. It simply shines a light in the right place, illuminating its corners and defying us to look away. The results are indelible, resonant, and deeply troubling: a statement that only the most foolish would dare dismiss.